Lever escapements



Dec. 6, 1960 J. A. REINHARDT LEVER ESCAPEMENTS Filed April 29, 1959 United States Patent-O 2,962,900 LEVER ESCAPEMENTS joseph A. Reinhardt, Wheaton, 111., assignor to Wheaton Engineering Corporation, Wheaton, Ill.

Filed Apr. 29, 1959, Ser. No. 809,651

8 Claims. (Cl. 74-15) This invention relates to lever escapements as used in time-rate mechanisms.

A principal object of the invention is to provide a lever for cooperation with a toothed escapement wheel which is of one-piece construction, including the pallets, and whereby the shape and location of the pallets may be initially established in accurate relation and therefore, because of their nonadjustable character, may not be tampered with or lose their original setting by reason of vibration.

Another object is to provide a one-piece lever for the purpose aforesaid which comprises a blank section upon which the pallets are cut and wherein variation in the disposition and configuration of the pallets may be varied at the time of manufacture depending upon the characteristics desired in the escapement of which the lever forms a part.

A further object is to provide a lever escapement characterized by virtually ideal isochronism arising out of a novel shape of teeth on the escapement wheel cooperative with a novel form of pallets.

Other objects and advantages will appear from the following description which, taken with the accompanying drawing discloses one mode of carrying the invention into practice.

In the drawing:

Fig. 1 is a perspective view of the escapement lever proper;

Fig. 2 is a somewhat schematic showing of the escapement wheel and pallets in one position of oscillation of the lever;

Figs. 3 and 4 are each a detail of a portion of Fig. 1 showing the lever in other positions of oscillation; and

Fig. 5 is an enlarged detail of a tooth of the escapement wheel.

Broadly regarded, the invention, in one aspect, comprises an escapement lever of one piece construction including a substantially cup-shaped central portion or hub which is essentially a longitudinally truncated, hollow cylinder. Two of the edges resulting from such truncation lying at opposite edges of a chordal plane of the cylinder are shaped as pallets for cooperation with the teeth of the escapement wheel. The hub is provided on its exterior with a pair of oppositely-disposed, radially-extending arms which may coact with fixed stops for limiting the amplitude of oscillation, and the distal end of at least one of the arms may carry a ferromagnetic button or equivalent for cooperation with a permanent magnet for regulating the period of oscillation. One end of the cylinder is closed and is axially perforate for reception of a shaft or its equivalent constituting the axis of oscillation. In another aspect, the invention comprises a novel form of tooth for the escapement wheel and of pallets for cooperation therewith.

Turning now to the drawing (Fig. 1) there is shown an escapement lever comprising a cup-shaped, hub including side wall portions 11 and 12, an end wall 13 and two radially-extending opposed arms 15. In accordance Ice with the invention the structure as just described is best achieved in practice by providing a suitable metal blank which is then deep-drawn in a die to provide a cylindrical cup and then longitudinally truncating the resulting cup by milling one side substantially along a chordal plane, as shown, to define edges 21 and 22 (Fig. 2). While the opposite side of the hub is also milled on a chordal plane 20 the edges thereby resulting are not shaped in any particular fashion as they have no function per se. The portion of the hub thus cut away assists in obtaining dynamic balance about the axis of oscillation AA. While the truncation may extend from the top wall 13 over the whole length of the hub it is preferred to terminate the same to define arcuate webs 14 which serve to rigidify the remaining parts of the hub. The top wall 13 is provided with an axial aperture 26 into which a shaft 27 or other bearing member may be secured to support the lever for oscillation.

The spatulate form of the arms 15 provides a distal end to accommodate a pair of weights of any desired mass for modifying the period of oscillation. One thereof may be ferromagnetic for cooperation with an adjacent permanent magnet mounted for adjustment whereby the period may be appropriately regulated.

Either set of edges such as 21 and 22 or their opposite counterparts may be utilized as pallets by appropriately conforming the same. In accordance with the invention the pallets take the form shown in Fig. 2 to which detailed reference will be made hereinafter.

By way of example the invention is shown as part of an escapement of novel form. Referring to Figs. 2 to 4, there is shown an escapement wheel 31 having a plurality of teeth 32 cooperative with the pallets 21 and 22 heretofore alluded to. In connection with the following description it will be understood that the lever 10 is supported for oscillation on the axis AA by means of suitable bearings '28, 29 and is constantly subjected to the restorative force of a spring 30, e.g. an elongated, straight, torsionally deformable wire, fixed at one end to the shaft 27 and at the other end to the framework 33 supporting the several members comprising the escapement. As will be understood, power is supplied to the wheel 31 through a gear train which therefore undergoes intermittent rotation by virtue of its cooperation with the lever-three of the positions of which are shown in Figs. 2 to 4.

In order to achieve virtually ideal isocrhonism the shape of the pallets and of the teeth take the form illustrated. The pallet 21 consists of a flat face disposed at an angle of substantially to a chordal plane B-B, e.g. 91, the plane being parallel to :a plane of symmetry through the axis AA. In the example the dimensions are as shown. The pallet 22 is provided with a flat face disposed at an angle of substantially 35 to the chordal plane. The outer edge of both pallets falls on the plane and the space between them is determined in accordance with the circular pitch of the teeth 32. In the example this dimension is 0.1886, the same being a function of the distance between the axial plane of symmetry and the plane B-B as well as the outer diameter of the hub 11.

The teeth 32 of the escapement wheel 31 have a configuration shown in detail in Fig. 5. For a wheel having 30 teeth the sides a and b of the tooth lie on tangent lines to a pair of base circles C and D having diameters of 0.1626 and 0.1788" respectively. Each side a and b terminates inwardly on base circles of c and d having diameters of 0.369" and 0.364" respectively, and terminates outwardly on base circles e and having diameters of 0.422" and 0.441" respectively. On its outer edge each tooth is curved on a radius g of 0.0195.

Several positions of the escapement lever are shown in'Figs; 2 to 4. In'Fig. 2 the pallet 22 is fully beneath a tooth 32a. With rotation clockwise the succeeding oscillation of the lever withdraws the pallet 22 from beneath the tooth 32a and the wheel moves (Fig. 3) with pallet 21 bearing on the end face of tooth 32b whereby it is cammed along the arcuate surface thereof to cause the lever to follow the motion of the wheel until pallet 21 can fall between a pair of teeth 32b and 32c (Fig. 4) whereupon the wheel is arrested by abutment of the tooth 320 on the exterior of the wall 11 of the lever. On the succeeding oscillation the action proceeds cyclically as in Fig. 2, as will be apparent.

While I have shown particular embodiments of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

I claim:

1. A lever escapement comprising: a framework, an intermittently rotatable toothed wheel pivotally mounted on said framework, a source of input power for pulsing the escapement, a lever pivotallymounted on said framework for oscillation comprising a cup-shaped member including an end wall having a central aperture for receiving the pivot, the lateral Wall of said member being longitudinally truncated for a predetermined distance intermediate the ends thereof to define longitudinally extending wall portions shaped on the free edges to present a pair of pallet surfaces for alternately releasably engaging the teeth of the wheel as the lever oscillates in response to input power, said member having a pair of diametrically oppositely disposed arms extending radially of said member having apredetermined radial length for initial establishment of the period of the escapement and bias means deformable in the direction of the pivotal axis secured at its ends to said framework and member respectively for restoring the lever after each oscillation thereof.

2. The combination in accordance with claim 1 further characterized by the provision of adjustable masses at the distal end of each arm for regulation of the period.

3. The combination in accordance with claim 1 characterized in that the lateral wall of said member is also truncated additionally on the side opposite said first truncation and symmetrically therewith for dynamic balance of the lever.

4. The combination in accordance with claim 1 wherein the teeth of the wheel comprise straight sides on lines tangential to a pair of base circles concentric with the axis of the wheel, said lines being divergent at the periphery of the wheel to define teeth which are, circumferentially, wider at the tip than at the root thereof, and

the leading pallet has a working surface constituted on the leading face by the curved plane of the exterior of the member and on the trailing face as a plane surface substantially parallel to that longitudinal mid-plane of the member which is perpendicular to the plane of truncation defining the pallets, and the trailing pallet has a working surface constituted on the leading face by the interior curved wall of the member and on the trailing face as a plane surface at an angle of substantially 36 to said plane of truncation.

5. A one-piece lever for a lever escapement comprising a substantially cup-shaped body of hollow cylindrical form including an end wall and a lateral wall longitudinally truncated along a portion thereof intermediate the ends thereof on a plane parallel to the axis to define a pair of exposed straight edges, said edges being wedge shaped to constitute pallets for cooperation with the teeth of the escapemerit wheel, and-shaft means secured in the end wall to support said body for oscillation.

6. A one-piece lever for a lever escapement comprising a cup-shaped, shell-like body of hollow cylindrical configuration longitudinally truncated along a portion of the lateral wall intermediate the ends thereof to definea pair of parallel, straight edge portions which are wedge shaped for cooperation with the teeth of the escapement wheel, said'body having a pair of integral arms extending radially from the rim of the body.

7. A lever escapement comprising an intermittently rotatable toothed wheel and a lever pivotally mounted for cooperation with said wheel for converting periodic motion thereof into step-by-step rotation of the wheel, said wheel comprising teeth which are bounded on substantially radial edges by lines tangential to a pair of base circles concentric with the axis of the wheel, said lines being divergent at the periphery of the wheel to define teeth which are, eircumferentially, wider at the tip than at the root thereof, said lever having a pair of pallets, the leading face of the leading pallet being a cylindrical surface concentric with the axis of the lever and the trailing face thereof being a plane surface substantially parallel to that longitudinal mid-plane of the lever which is perpendicular to the plane through the free edges of both pallets and the trailing pallet having a cylindrical leading face concentric with the axis of the lever and a trailing face which is a plane surface at an angle of substantially 36 to said first plane surface.

8. The combination in accordance with claim 7 further characterized in that the outermost substantially circumferentially directed face of the tooth is defined by an arc of a circle which is smaller in diameter than the circle defining the periphery of the wheel and the center of said smaller circle lies substantially on the trailing straight side of the tooth.

References Cited in the file of this patent UNITED STATES PATENTS 2,061,047 Schweitzer -2 Nov. 17, 1936 2,092,216 Junghans Septj7, 1937 2,385,011 Lur tz Sept. 18, 1945 2,406,730 Whitehead Aug. 27, 1946 FOREIGN PATENTS 777,406 Great Britain June 19, 1957 

